An important part of animal metabolic studies involves the study of the nutritional state, and the gastrointestinal and renal function of the animals. Metabolic enclosures typically provide for the collection of feces and urine but these metabolic end products are often contaminated with spilled food and neither the spilled food nor the animal wastes can be recovered quantitatively. What is needed is an apparatus for reducing food spillage and a means of catching spilled food to accurately determine food consumption and to prevent the spilled food from contaminating measurements of urine and fecal output.
U.S. Pat. No. 4,785,765 discloses a laminar diffuser which includes an inclined serrated linear ramp which directs the urine to a urine collection vessel and by its configuration, transports the feces past the urine collection vessel without mixing the two. This device has no apparatus for preventing spilled food from entering the fecal collector.
U.S. Pat. No. 2,684,051 and Canadian Patent No. 689,018, disclose a cage for laboratory animals having wire mesh walls and floor that allows animal droppings to pass through the floor into a funnel shaped container situated at the bottom of the cage where urine and feces are separated. The device also includes a metal food cup that is bolted to the floor of the cage and a rim that acts as a baffle to prevent the animal from scattering food particles over the wire mesh floor. The device does not measure spilled food and the wire mesh walls of the cage allow some food particles to leave the cage and not be accounted for.
U.S. Pat. No. 3,107,650 discloses a funnel shaped apparatus for separating feces from urine and preventing the loss of urine volume due to evaporation in laboratory animals. Contamination of the metabolic output by food is not covered in this invention.
U.S. Pat. No. 3,227,139 discloses a disposable animal metabolic cage that separates solid from liquid animal waste, prevents the evaporation of liquid waste and provides for the removal of solid and liquid waste without personal contact with any contaminated components. This device does not address contamination of the waste matter by spilled food.
U.S. Pat. No. 4,154,196 discloses an animal metabolism unit which is an improvement by the same inventors of U.S. Pat. No. 3,227,139. The device disclosed in the later patent reduces evaporation of liquid animal waste and affords ready access for removal of animal waste products.
U.S. Pat. No. 5,163,380 discloses a device for measuring food, water and oxygen consumption and the resulting metabolic outputs of laboratory animals on a real time or near real time basis, using telemetry. A radio-frequency transducer is embedded within the animal, and transmits heart rate, body temperature and blood pressure. The device is used for testing pharmacologically active substances on laboratory animals with known metabolic and psychologic characteristics in a sterile environment, where the testing itself is of short duration.
In many metabolic cages, the food dish is designed in such a manner that the animal can stand or sleep in the food and scatter it beyond the dish where it can mix with the discharged urine or escape the cage. There is a need or an improved feeder that reduces the chance of food spillage, allows any spilled food to be measured and keeps spilled food out of collected urine.